Field of the Invention
The present invention relates to a circuit for controlling hydraulic pressure of a torque converter applied to an automatic transmission for a vehicle. More particularly, the present invention relates to a circuit for controlling hydraulic pressure of a torque converter capable of improving an engagement response feature of a lock-up clutch embedded in a torque converter for a 3-way separate chamber multi-plate clutch structure.
Description of the Related Art
Since a torque converter applied to a vehicle transfers a torque by rotating a turbine using a fluid as a medium, it has a disadvantage in that a torque may not be fully transferred in a general friction clutch. Therefore, the torque converter includes a lock-up clutch that may directly transfer the torque mechanically in a high speed region.
The lock-up clutch is disposed in a space part formed between a front cover, which is an input side rotating member of the torque converter, and a turbine, which is an output side rotating member of the torque converter, and is controlled so as to be operated or so as not to be operated by hydraulic pressure supplied to a hydraulic pressure chamber for engagement of the lock-up clutch.
In addition, the hydraulic pressure supplied to the hydraulic pressure chamber for engagement of the lock-up clutch is controlled by a torque converter control valve and a linear solenoid valve. Recently, the hydraulic pressure supplied to the hydraulic pressure chamber for engagement of the lock-up clutch has been directly controlled using the linear solenoid valve.
However, in the case in which the lock-up clutch is controlled using the linear solenoid valve as described above, an operation control of the lock-up clutch is controlled regardless of hydraulic pressure in the torque converter. Therefore, in the case in which the hydraulic pressure in the torque converter is large, the operation control of the lock-up clutch becomes slow, such that stability in controlling the lock-up clutch is decreased.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.